Process of paper making



Patented May 21, 1929.

UNITED STATES LEVIS MILLER BOOTH, OF PLAINFIELD, NEW JERSEY.

PROCESS OF PAPER MAKING.

No Drawing.

This invention relates to a process of re taining in the newly formed web of paper or board a higher percentage of sizing, filler,

etc., than is possible by means heretofore practiced.

With a view to improving the writing, printing or water proof qualities of paper or board or to increasing the durability and to provide a more attractive finished sheet,

certain grades of paper while in the preliminary stages of manufacture are treated with an emulsion of soda ash and resin and subsequently or before are treated with sulphate of aluminum. The latter is used to effect a precipitation of the resin and also to provide a vehicle for the distribution and retention of resin. The alumina-resin combination adheres in part to the fibers of the paper making pulp and produces the effect designated as sizing in the finished paper. The

size-alum recess is usually applied to the stock in t e beaters. Filler such as clay or other inert material when used is also applied in the beater or later in the precess.

Because of the nature of the paper'making fibers only portions of the resin of the size and the filler furnished remain in the sheet of paper. The unretained balance is drained oif with the white water during the formation of the paper.

I have found that the addition of freshly preppred metallic hydroxide a plied to the stoc just previous to the de ivery to the paper mac'hme, has the effect to cause the retention of more of the resinous material and filler in the paper bein formed and hence improves the sizing quality and finish of the paper made by my process. Besides, an economy of chemicals is eifecte because less of size, etc., is wasted by being llowed to run ofi with the white water.

In practice for the purpose of producing an eflicient absorbent I. have added a mixture of soda ash and sulphate of aluminum in the ratio of 32 to 68, to the stock at the head box on the paper machine. This ratio may be varied to suit the requirements, depending upon the quality of the stock applied ,to the machine and the desired characteristics of the finished aper. Instead of feeding soda ash and sulp ate of aluminum as a dry mixture, these may be added separately, either dry or in solution. Other substances than those mentioned above may be used without departing from the spirit of this invention Application filed February 8, 1928. Serial No. 252,944.

.salt or a combination of iron salts. I have also successfully used a mixture of calcium carbonate and sulphate of aluminum for the production of aluminum hydroxide. In this case a double reaction results which involve, first the evolution of carbon dioxide by the action of the acidity of the aluminum sulphate component. The carbon dioxide in turn forms a soluble salt, calcium bi-carbonate, and this reacts with the dissolved sulphate of aluminum to produce aluminum hydroxide.

My process is to be distinguished from any wherein a primary precipitation of the size-alum precipitate occurs, but involves coagulation of the finely divided resinous precipitate already formed but which due to a high degree of dispersion is readily drained off and lost during the formation of the paper or board.

Since I employ a mixture of acid and alkaline components in m coagulant, mixed in substantially chemica 1y equivalent proportions, I do not cause anyastringency of the fibers. In fact I have found it possible to effect good sizing of container board and at the same time to permit a reduction in the ratio of alum to size furnished for the primary sizing precipitate, thereby reducin the acidity of the sized product. This is a vantageous because with a reduction of acidity there is an accompanying increase in the strength of the paper or board made.

The primary reason when usin heretoo0 fore known processes for maintaining acidity in sized pa er is to insure efiicient size precipitation. y my process the addition of the components necessar to produce a freshl prepared non-colloi a1 metallic hy-, droxi e precipitate, at a time and under conditions when a coagulating precipitate is most effective the size-alum precipitate is retained in the sheet and the paper or board contains less of strength deteriorating acidity than heretofore customarily maintained.

Claims:

1. The process of making paper consisting of adding substances to roduce a metallic hydroxide to pa er ma ing stock subsequently to the ad ition of size and sizerecipitating chemicals and at or before de ivery to the paper makin machine.

2. The process of ma ing paper consistin of adding an alkaline substance and a me of addin soda ash and sulphate of aluminum to tEe paper makin stock at or before delivery to the paper ma ing machine.

6. The process of making paper consisting of adding soda ash and sulphate of aluminum to aper making stock subsequently to the addition of size and size precipitating chemicals at or before delivery to the paper making machine.

7. The process of making paper consisting of adding substances causing the production of a coagulating precipitate in the presence of the paper making stock at or before the delivery to the paper making machine.

' LEVIS MILLER BOOTH. 

